Dosing dispensers for the addition of laundering and softening materials during the washing and rinsing cycles in an automatic washing machine are well known in the art.
Dispensers for adding materials during the rinse cycle in an automatic washer are generally more complex than those employed for adding materials during the wash cycle due to the fact that the rinse additive dispenser is normally inserted when the wash cycle begins and must survive the entire wash cycle without dispensing the material contained inside, yet reliably open during the spin cycle at the conclusion of the wash cycle to deliver the rinse water additive at a point in time which will be effective.
One prior art example of such a rinse water additive dispenser is disclosed in commonly assigned U.S. Pat. No. 3,888,391 issued to Merz on Jun. 10, 1975 and hereby incorporated herein by reference.
Another example of such a prior art rinse water additive dispenser is disclosed in U.S. Defensive Publication No. T993,001 to McCarthy, which was published on Apr. 1, 1980, and which is hereby incorporated herein by reference.
Dispensers of the aforementioned type employ a valve means which is automatically opened by centrifugal forces acting upon a counterweight during the spin cycle at the conclusion of the wash operation. After the spin cycle, dispensers of the aforementioned type fall from the wall of the washing machine drum and rinse water floods the dispenser, mixing with and dispensing the additive into the rinse water.
While dispensers of the aforementioned type have functioned adequately for their intended purpose with prior art rinse water additives, recent trends in the development of more effective rinse water additives have been in the direction of more highly concentrated products which deliver comparable performance benefits to the less concentrated products which they are tending to replace. For example, one fluid ounce of a highly concentrated fabric softener, such as Ultra Downy.RTM. now being marketed by The Procter & Gamble Company of Cincinnati, Ohio, can deliver benefits comparable to three fluid ounces of a less concentrated fluid softener product of the type which has been on the market for several years.
However, to obtain maximum performance benefits from the newer more highly concentrated products, accuracy of measurement has become much more critical. In addition, it has become much more critical that substantially all of the additive material initially placed in the dispenser be retained within the dispenser during the wash cycle, since any lost additive material will not be available to accomplish its intended objective during the rinse cycle.
Prior art rinse additive dispensers of the type described earlier herein are generally spherical in shape and employ a fill mark to indicate when the desired amount of additive has been poured into the dispenser. While the fill mark approach in a spherical dispenser has worked well for products which are relatively dilute (when compared to the more highly concentrated products being marketed today) when the volume of product to be added is quite small accurate measurement thereof is quite difficult to achieve with prior art style dispensers because even a slight deviation from the fill mark represents a substantial change in product volume, i.e., the cross-section of the sphere increases rapidly in the area of the fill mark so that slight deviations from the fill mark represent substantial deviations in the amount of product actually included within the dispenser, particularly if the user overshoots the fill mark.
In addition, it has been observed that prior art dispensers of the type described earlier herein may tend to lose some of the additive initially placed in the dispenser during the wash cycle due to flexing of the valve member during the wash cycle, even though the valve may remain in a substantially closed condition until the dispenser is subjected to a spin cycle. This loss of product also negatively impacts the benefits provided by highly concentrated rinse additives, since their loss during the wash cycle renders them unavailable to impart benefits to the laundered fabrics during the rinse cycle. Loss of the highly concentrated additive is particularly detrimental, since it results in a greater loss of the active materials when compared to less concentrated fluid product forms.